/* Formatted on 2017/09/21 오전 10:52:04 (QP5 v5.256.13226.35510) */
WITH T
      AS (SELECT '강호동' AS USER_NM
                    ,1 AS LEV
                    ,'a' CD
                    ,'' AS UP_CD
              FROM DUAL
            UNION ALL
            SELECT '유재석' AS USER_NM
                    ,2 AS LEV
                    ,'b' CD
                    ,'a' AS UP_CD
              FROM DUAL
            UNION ALL
            SELECT '홍길동' AS USER_NM
                    ,3 AS LEV
                    ,'c' CD
                    ,'b' AS UP_CD
              FROM DUAL
            UNION ALL
            SELECT '강감찬' AS USER_NM
                    ,4 AS LEV
                    ,'d' CD
                    ,'c' AS UP_CD
              FROM DUAL)
  SELECT DECODE (A.LEV, 1, A.USER_NM) NM1
          ,DECODE (A.LEV, 2, A.USER_NM) NM2
          ,DECODE (A.LEV, 3, A.USER_NM) NM3
          ,DECODE (A.LEV, 4, A.USER_NM) NM4
          ,CD
          ,UP_CD
          ,lev
     FROM T A
ORDER BY CD

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